Flashrom is an open source utility for working with flash storage chips. It supports a bunch of flash chips commonly used on motherboards to hold the system BIOS. biosflasher (Carl-Daniel Hailfinger) recently added Bus Pirate support to Flashrom.
Now pgeorgi has released a Windows port of Flashrom with Bus Pirate support, and biosflasher committed the patches back to the Flashrom repository. Check out the usage examples in the forum.
Great work, thanks for making the Bus Pirate the best supported universal serial interface around!